1. Field of the Invention
The present invention relates to a method and a system for providing binaural hearing assistance to a user wearing a right ear unit at the right side of his head and a left ear unit at the left side of his head, with each ear unit comprising a microphone arrangement for capturing audio signals at the respective ear unit and means for stimulating the respective ear of the user, and with the ear units being capable of exchanging audio signals. Usually the ear units will be hearing aids. In most cases the stimulating means will be loudspeakers, while also other stimulating means are perceivable, such as electro-mechanical transducers (e.g. DACS (Direct Acoustic Cochlea Stimulation) or CI (Cochlea Implants)). According to another aspect, the invention relates to a method and a system for providing hearing assistance to a user wearing a right ear unit at the right side of his head and a left ear unit at the left side of his head, with each ear unit comprising a microphone arrangement for capturing audio signals at the respective ear unit, with one of the ear units comprising means for stimulating the respective ear of the user, and with the ear unit not having stimulating means being capable of transmitting audio signals to the other ear unit.
2. Description of Related Art
Binaural hearing aid systems are used to enhance the intelligibility of sound signals, in particular speech signals in background noise. In binaural systems both audio signals and control/status data may be exchanged between the two hearing aids, typically via a bidirectional wireless link. The exchanged audio signals may be mixed with the audio signals captured by the microphone of the respective hearing aid, for example for binaural acoustic beam-forming. Examples of such binaural systems can be found in US 2004/0252852 A1, US 2006/0245596 A1, WO 99/43185 A1, EP 1 320 281 A2 and U.S. Pat. No. 5,757,932.
According to US 2004/0252852 A1 a binaural beam-forming technique is applied wherein the left ear audio signal and the right ear audio signal are mixed prior to being reproduced by the loudspeakers of the hearing aids, with the ratio of the noise power in the right ear audio signal and the noise power in the left ear audio signal being used as a parameter for adjusting the audio signal mixing ratio. If the noise power is equal in both audio signals, the audio signals are mixed with equal weight. The mixed audio signal may be provided as a monaural signal to both ears, or mixing may occur separately for both ears.
According to US 2006/0245596 A1, binaural audio signal mixing occurs in such a manner that the captured audio signals are exchanged between the two hearing aids and that for each frequency range that signal having the higher level is reproduced at both ears. According to one embodiment, such mixing algorithm may be applied only to the frequency range of speech, whereas for other frequencies the signal is removed or is reproduced as a stereo signal.
According to WO 99/43185 A1 the binaural audio signal mixing is controlled in such a manner that for persons with a binaural hearing loss binaural sound perception is restored while taking into account the difference in hearing loss and compensation between the two ears.
According to EP 1 320 281 A2 the binaural audio signal mixing is controlled according to the presently prevailing acoustic environment and/or the time development of the acoustic environment.
According to U.S. Pat. No. 5,757,932 the binaural audio signal mixing is used for achieving binaural acoustic beam forming.
EP 1 439 732 A1 relates to a hearing aid which may be part of a binaural system and wherein the captured audio signals are split into a main path and a side path prior to being processed, with the processing of the side path resulting in smaller group delay than the processing of the main path, and with the two paths being added prior to being supplied to the loudspeaker. This method utilizes the “precedence effect”, according to which the first wave front determines the spatial localization, in order to avoid localization problems due to group delay caused by signal processing in the frequency-domain.
Further, it is known to use so-called “CROS” or “BICROS” systems for aiding single sided deaf persons, i.e. persons having a very asymmetric hearing loss. In such systems audio signals captured at the deaf ear are transmitted to the better ear in order to be reproduced by a loudspeaker to the better ear. If necessary, the better ear will be aided by a hearing aid, in which case the audio signals transmitted from the deaf ear are combined with the audio signals captured at the better ear prior to being reproduced by the loudspeaker at the better ear.
It is a first object of the invention to provide for a method and a system for providing binaural hearing assistance, wherein the perception of target audio signals in background noise should be improved, in particular for hearing impaired persons.
It is a second object of the invention to provide for a method and a system for providing hearing assistance to persons suffering from severe strongly asymmetric hearing loss, wherein the perception of target audio signals in background noise should be improved.